Genetic panel for the English Setter covering neuronal ceroid lipofuscinosis type 8 (NCL8, CLN8) and crd4-PRA progressive retinal atrophy, which in this breed is caused by compound heterozygosity of two modifiers: RPGRIP1 (Cord1) and MAP9 (OMIA:001432).

Applicable breed: English Setter (NCL8). PRA: exists clinically in the breed without a known gene; NCL8 carrier frequencies: limited data.

- Reduced vision and progressive retinal atrophy of late onset (crd4-PRA)\n- Progressive neurological signs: ataxia, myoclonus, behavioural decline, blindness (NCL8)

NCL8 due to CLN8 c.491T>C was described in the English Setter (Katz 2005). PRA in the English Setter exists clinically but without a known gene: in a multi-breed screening, most breeds with known PRA showed cases with none of the known mutations (Downs et al. 2014). The crd4 (RPGRIP1, Dachshund/Springer) and rcd4 (C2orf71, Gordon/Irish Setter) forms belong to other breeds and should not be extrapolated to the English Setter.

- Test NCL8 (CLN8) in breeding dogs before mating.\n- Do not mate two NCL8 carriers: 25% risk of affected homozygotes.\n- There is no validated test for PRA in the English Setter: maintain annual ophthalmological examination (ECVO) of breeding dogs and do not attribute results from tests for other breeds.\n- After a confirmed case, do not repeat the mating and communicate the status.

PRA in the English Setter is a clinical and ophthalmological diagnosis (ERG, fundus examination); no PRA test from another breed (crd4/RPGRIP1, rcd4/C2orf71, prcd/PRCD) covers it. NCL8 is confirmed by the CLN8 test. Differential diagnosis of juvenile ataxia with other encephalopathies.

1. Forman OP, et al. Frequency of RPGRIP1 and MAP9 genetic modifiers of canine progressive retinal atrophy, in 132 breeds of dog. Anim Genet. 2024;55:687-691. PMID 38752391. 2. OMIA:001432-9615 (crd4-PRA).